Posted
by
samzenpus
on Thursday March 18, 2010 @12:18PM
from the hoping-each-time-that-his-next-leap-will-be-the-leap-home. dept.

SpuriousLogic writes "A team of researchers have created a 'quantum state' in an object billions of times larger than ever before. From the article: 'Such states, in which an object is effectively in two places at once, have until now only been accomplished with single particles, atoms and molecules. In this experiment, published in the journal Nature, scientists produced a quantum state in an object billions of times larger than previous tests. The team says the result could have significant implications in quantum computing.'"

I don't need to be told that it's "billions of times than ever before", or to compare it to the library of congress, I can understand measurements. so how big is the object? 1 nanometer? 1 kilometer? what? the article doesn't seem to say either.

I don't need to be told that it's "billions of times than ever before", or to compare it to the library of congress, I can understand measurements. so how big is the object? 1 nanometer? 1 kilometer? what? the article doesn't seem to say either.

It's the Library of Congress.

It's now simultaneously at its usual place and two hundred miles under the sea.

Some have said this is a small thing. That is 10 times greater than the size of the human genome in atoms.
I had a thought, if the transporter held an anti-copy and as long as the anti-copy
existed, the real person would exist at some distant point. When the anti-copy is destroyed it returns the person to the teleporter.
It seems that from my understanding of the process that this would in fact produce an effective object at the remote point. I suppose it could be considered the inverted object of a lens s

"In order to find the overall probability amplitude for a given process, then, one adds up, or integrates, the amplitude of postulate 3 over the space of all possible histories of the system in between the initial and final states, including histories that are absurd by classical standards."

So, for a photon that goes trough one or the other slit, you integrate over both, and you end up with the interference pattern in your

You do integrate through both slits, but that does not mean that every photon has actually gone through them. It's a mathematical technique.

What one proves experimentally is that if the which-path information exists (somewhere), there's no interference pattern. To infer from this that it went through both slits is, at best, non-sequitur, and at worse, philosophy.

Also

But from photon's perspective...

there's no photon's perspective. It makes no sense to try to Lorentz-transform you into a referential that's moving at the speed of light. I u

That's the problem with vague claims in an article. We don't know if the weight is billions of times bigger or if the diameter is. Therefore we don't know if we have 6x10^9 atoms or 6x10^27 atoms. It doesn't even give an order of magnitude -> epic fail of scientific journalism.

Trudat. But if we apply a little simple logic, we see that (for silicon at least), 10^27 atoms is about a cubic meter. They probably meant that the volume was increased by that factor which would make it closer to about a micron I'm guessing. Anything else wouldn't make much sense.

"As far as mechanical objects are concerned, the dividing line was at around 60 atoms," Professor Cleland said.
"With this experiment, we've shown that the dividing line can be pushed up all the way to about a trillion atoms."

ooh ooh! I just came up with an awesome idea to make money!Tell people you have a quantum teleporter that will make a copy of them on another planet, but in reality, it doesn't do anything, but they can't prove it because they can't get to the other planet.

we could make a religion out of it or something. Make loads of money. *ca ching!*

And then destroy the 'original' and 'send' their assets to the other planet (or your offshore account). Maybe that's Step 2? People who would actually believe Step 1 would probably believe it all the way...

"Your ideas intrigue me and I would like to subscribe to your newslett..."

Ah, screw that. I want in.

How much for a cut in to the action? I'm good at woodworking, and can probably make the Quantum Duplication Cubicles for you. I also have a background in sales, and a 20+ year career in IT, so I can make the lights go blinkie and help with the marketing fluff.

You have to destroy the original, otherwise he may sue you, once he figures out that you didn't actually copy him. So this is going to be a messy business model and you should hook up with an undertaker...

How am I supposed to know if I haven't seen it if the name of the movie is in the spoiled text itself? What next, "Spoiler alert: stop now if you don't know that Darth Vader is Luke's father" or "Spoiler alert: stop now if you don't know about the stuff that happens after Aeris dies"?

They think it 'could have' significant implications?Surely they mean it definitely has significant implications and also hasn't?

Nah, that's just wishful thinking. Obviously whether it has significant implications is still in an uncollapsed state, but they're hoping it will collapse into the 'significant implications' state. Hmm, maybe Schrodinger wasn't trying to kill his cat after all...

We have carefully considered (not) your proposal and have decided to unconditionally release (or not) Schroedinger's cat. Therefore you may (or may not) find this free-range cat at a position which we will disclose (or not) at a later occasion, only under the condition that we cannot disclose the momentum of said cat.

From what the article looks like, all they've done is created a BEC (They don't mention that in the article, am I off?) of the largest object yet, which just means they cooled the material to milli-kelvin using some kind of trap, and the material becomes a new state of matter, a Bose Einstein Condensate.

For some reason, I expected some kind of two-slit or uncertainty principle thing with a very large object. This doesn't really seem that impressive to me, but then my quantum is a bit dated.

I have a question that I assume has a reasonable answer, just one I've never actually gotten confirmation on.

Once they've placed this object in a quantum state, how do they verify that it's "occupying two states at once?" Do they just measure it and repeat the process several times, and note that it's occasionally at 1 quanta, occasionally at 0, and from that infer that it was in a quantum state up until they measured it?

Second question, while I'm here - am I right in saying that according to the many-worlds interpretation, the universe branches when this object enters a quantum state, and we end up in one of two universes, one where the object has 1 quanta of energy and one where it has 0?

Actually in an object of this size you could plainly see it with the naked eye. Because the whole object would start to act like one particle. Which in practice means that you can see waves moving over it in a weird fashion, where particles annihilate and amplify each other.I once saw a video* of it, and it looks really cool. And veery creepy at the same time, when you realize what that means. (Imagine there being two cubes of steel matter in that state. You could not only shove them together to the exact s

I don't know about this experiment, but in the double-slit experiment, you can confirm that the photons pass the slit unobserved(in wave form) when you get a peculiarly structured hit pattern on the wall with the photoreactive film that can only result from the adding and cancelling of two wave distributions.

According to the Everett interpretation, http://www.hedweb.com/manworld.htm [hedweb.com], the universe will split at the time of the observation, not at the time of being placed in wave state, at least that is what

Once they've placed this object in a quantum state, how do they verify that it's "occupying two states at once?"

Interference phenomena. The article is light on detail, but presumably they excite the system into a superposition of (mechanical) normal modes and then observe the motion, or the position of some part of it, at a later time and find that it is in a classically forbidden region.

For example, suppose they excite it into two modes that interfere to produce a node at some point, so there is no motion there, but there would be if there it was in one mode or the other. Then monitoring the motion at that point would allow you to determine if the system was in a superposition of two quantum states rather than one or the other.

With regard to the many-worlds interpretation: it doesn't answer the really important question. Neither does consistent histories or any of the decoherence-based approaches. The really important question is, "Why is there a classical world at all?" That is, these theories purport to show that we can get along just fine without the wavefunction ever undergoing "collapse", so in some sense all possible quantum outcomes of an experiment are permitted. But they never answer (or even ask), "Why is it only via interference phenomena that we are aware of these effects? Why aren't we aware of the other components of the wavefunction all the time? Why is there a classical world at all? Is it a feature of consciousness or the physics that permits beings like us to exist, that we are selected by a basically anthropic process to be able to experience only the narrowest subset of existence? If so, how?"

Apart from that, the article is badly misleading: it seems to suggest that anyone anywhere thinks there is anything interesting about the physical size or number of particles involved the detectability of quantum phenomena. It has been known for decades that this is not the case: the number of available modes is what matters, and any sufficiently cold object can become arbitarily large without exhibiting classical behaviour. Furthermore, phenomena like the Mossbaure Effect told us something similar half a century or so ago. It's probably time for the popular press to stop talking about the quantum equivalent of the luminiferous aether and get with the 21st century.

Similarly macroscopic quantum states have been achieved in superconductors. So the significance of this work is that macroscopic superposition is accomplished with a mechanical system, not an electronic one.
The Nature article that the BBC is referring to:
http://www.nature.com/nature/journal/vaop/ncurrent/full/nature08967.html [nature.com]
The BBC removed the scale bar, which shows that the resonator is about 70 microns long, with an "active region" 40 microns long. But the resonant frequency is still up in the GHz, so they only have to cool to 0.1K, which is not so hard these days.

If it is true that '"I don't think there is a limit, that there will be a certain size where quantum mechanics starts to break down," Dr Aspelmeyer said,' then that means that even larger objects also go into superpositions of quantum states. That would go all the way up to human sized and larger. This is the fundamental principle of the Many-Worlds Interpretation (MWI), that when quantum measurements occur, even though we only see one outcome, actually we go into a superposition of multiple states, each of which sees a different outcome. Each state evolves independently. It is as though the world splits into parallel universes, where every possible outcome occurs in a different universe.

This follows strictly from the principle that QM applies at all sizes. And this new experiment certainly pushes us in that direction.

Some scientists, notably Roger Penrose, had speculated that QM would break down at macroscopic sizes. He specifically proposed that once sizes were large enough for gravitational forces to exceed some threshold, QM would break down. Wikipedia [wikipedia.org] has this: "Tiny superpositions, e.g. an electron separated from itself, if isolated from environment, would require 10 million years to reach OR threshold. An isolated one kilogram object (e.g. Schrödinger's cat) would reach OR threshold in only 10^-37 seconds." Now here we have a trilliion atom object. That is about 10^13 amu, which is 10^-14 kg. Dividing 10^-37 seconds by 10^-14 we get 10^-23 seconds, which is far shorter than this experiment lasted. This means basically that this experiment disproves Penrose's theory! This is the first time this has happened, and I am (AFAIK) the first person to notice this.

In short it is becoming harder and harder to avoid accepting the reality of parallel worlds. What this should mean for our actions is up to the philosophers, but we should not bury our heads and pretend it isn't true.

"I am convinced that science is getting us closer and closer to God. Pretty soon we're going to understand how the universe works and He's going to say "you figured it out! Come up to My kingdom!" and we'll get to go to Heaven. Blessed be!"

So, I'm "actually" communicating with people at multiple disparate location, while remaining in one location, making me "effectively" in two places at once. My virtual presence can have an actual effect on those actually present, making me ef

The object is not in two places at once. The quantum wavefunction of the object has non-negligible probability in two places at once. This means that the object is equally likely to be found in two different locations.

The wording of the article is extremely sloppy. Remember that a wavefunction is not the object. The wavefunction is nothing more than a way to calculate the probability of finding the object in a particular place. A better description of where the object is when it is in superposition is "nowh